Epoxide finish additive

ABSTRACT

Epoxides as adhesion promoting agents are added to the finish or spinning composition applied to tire yarn used in making tire reinforcing cord as a means of promoting adhesion between the cord and the rubber when using a conventional R/F/L adhesive.

United States Patent [191 Bhakuni et a1.

EPOXIDE FINISH ADDITIVE Inventors: Roop S. Bhakuni, Copley; Joseph-L.

Cormany Jr., Akron, both of Ohio Assignee: The Goodyear Tire & Rubber Company, Akron, Ohio Filed: Oct. 29, 1971 Appl. No.: 194,045

Related US. Application Data Continuation-in-part of Ser. No. 78.251. Oct. 5. 1970. Pat. No. 3.718.587.

[ 1 Apr. 9, 1974 [56] References Cited UNlTED STATES PATENTS 3,297,467 1/1967 Macura et a1 161/110 X 2,829,071 4/1958 Schroeder 117/1395 Primary E.\-aminer1-1erbert B. Guynn Attorney, Agent, or FirmF. W. Brunner; V. G. Parker; .1. P. Ward [5 7 ABSTRACT Epoxides as adhesion promoting agents are added to the finish or spinning composition applied to tire yarn used in making tire reinforcing cord as a'means of promoting adhesion between the cord and the rubber when using a conventional R/F/L adhesive.

1 Claim, No Drawings EPOXIDE FINISH ADDITIVE This application is a continuation-in-part application of our application Ser. No. 78,251 filed Oct. 5, 1970 now US. Pat. No. 3,7l8,587.

This invention relates to an improved tire yarn finish and to an improved laminate of rubber reinforced with a cord made of the yarn coated with the finish containing an adhesion promoting agent which promotes a bond between the cord and the rubber as in a pneumatic t-ire when using a conventional R/F/L adhesive applied to the finish treated cord prior to embedment in the rubber.

Pneumatic tires are being subjected to increasingly severe operating conditions, especially high speeds, heavy loads, and accelerated braking and the performance of the tire under these conditions depends in large part upon the durability of the adhesive bond developed between the reinforcing cord and the rubber being reinforced. The bond is formed between active sites in the rubber and on the surface of the cord. The filaments in the yarn used in making the cord are coated with a finish to provide proper lubrication during the drawing and twisting operations in making the cord. lt has been observed that the finish interferes with maximum bonding of the cord to the rubber.

It has now been discovered that this difficulty can be overcome without loss of any function performed by the finish by adding an adhesion promoting agent to the finish.

Even though the adhesion promoting agent is added to the finish, the finish still achieves a satisfactory. lubrication of the filaments with a minimum of friction throughout various drawing, spooling, winding, transporting, twisting, cording, weaving and similar textile operations while still providing improved bonding between the cord and the rubber. i

It is especially desirable to apply this adhesion promoting agent to the finish immediately after the filaments have been spun from, for example, molten polyester and before stretching or fiber orientation of the polyester in a conventional manner as by dipping, spraying, or padding. Thereafter the yarn is heated over hot rolls at about 160 C. to about 255 C. in steps normally required for drawing and heat setting the filaments. The filaments are then made into a tire cord and a modified resorcinol/formaldehyde adhesive dip (R/F/L) is applied in a conventional manner to the cord.

The tire yarn finish base coating composition of this invention may be applied to many types of tire yarn including such natural fibers as cotton, regenerated cellulose fibers such as rayon, synthetic fibers such as polyamides and known generally as nylon, synthetic fibers of polyacrylonitrile generally known as acrylon, and synthetic fibers of polyesters, specifically'fibers of polyethylene terephthalate known generally by the trade names Dacron, Vycron, etc.

Finishes useful in this invention are those used in the fiber industry primarily as a lubricant to minimize friction between the filaments and metal rolls during the drawing operation. Generally these finishes comprise a lubricating oil, an antistatic agent, and an emulsifier. The lubricating oils include such substances as palm oil, coconut oil, cottonseed oil, mineral oil, glycerides, polyglycol esters, butyl stearate, octyl stearate, esters of oleic acid, trimethylol propane/caprylic acid esters,

invention include such cationic agents as quaternary ammonium-, pyridinium-, imidazolinium-, and quinolinium function, phosphated alcohols and ethoxylated- I amides.

Water miscible organic solvents such as benzene may also be used in forming the finish for such lubricants as paraffin oils, i.e., saturated aliphatic hydrocarbons boiling in the gasoline range.

The nonionic emulsifying agents" are referred to in detail by Swartz et al. in Surface Active Agents published by lnterscience Publications l ncorporated (1949) starting at page 202, and their use with textile lubricants is described in detail by Swartz et al. in Surface Active Agents and Detergents, Volume II, by Interscience Publication Incorporated (195 8) starting at page 596. The terms fatty acids and fatty alcohols" used in connection with describing the emulsifying agents refer to fatty acids and their corresponding alcohols having an aliphatic hydrocarbon chain of from O8 to C-l8 or more and'are usually derived from natural sources and are usually mixtures of various chain length but the corresponding synthetic compounds may also be used.

The finish is prepared generally by mixing a blend of the lubricating oil with water to a 25 percent solids concentration and then adding the adhesive .bond promoting agent to the oil-water mixture, or to the oil prior to mixing with water, and forming an emulsion thereof in warm water and adding sufficient alkali if necessary to adjust the pH from about 8.3 to about 8.5.

It has been found that the polyepoxides will produce the desired improvement in bond strength between the rubber and the polyester tire cord when added to the finish. The polyepoxides that function to produce improved adhesions are any of the polyepoxides disclosed in US. Pat. No. 3,247,043 and which are substantially soluble in water or emulsifiable thereon. Particularly desirable polyepoxides are those based on the reaction of epichlorohydrin with pentaerythritol (conveniently referred to as EPCP) and with glycerine (conveniently referred to as EPCG) wherein the epoxy group is present in an amount greater than 0.2 equivalent per grams of epoxy material as determined by standard analysis.

The adhesion promoting agent is added to the finish in amounts from about 0.05 parts to about 30 parts per 100 parts of lubricating oil present. The finish when applied to the filament is present in an amount between about 0.3 to about 1.5 parts per 100 parts of filament. The adhesion promoting agent may be added to the finish by blending into the oil or by blending into the water before or after the oil is added to the water or dissolved in a solvent and then blended into the oil. The pH of the mixture is to be adjusted as noted before de- Amount Ingredients Preferred Range Lubricant 70% 60-75% Antistatic agent 20% -30% Emuls'ifier 10% 10-20% The finish composition is applied to the tire yarn at a point below the spinneret in the form of a dilute aqueous emulsion, the concentration of which is varied as desired in accordance with the amount of finish to be applied to the yarn. The dried yarn may contain from about 0.3 to 1.5 percent by weight of the yarn of the finish composition.

A polyethylene terephthalate filament was coated in each instance with the finish containing the adhesion promoting agent by a scotch roll using a 25 percent solids emulsion of the finish on the filament at a point below the exit end of a 190 hole spinneret. The filaments are then spun at a spinning speed of 150 yards per minute to give a single spun yarn having a total denier of approximately 7,800, which yarn is then passed to a pair of rotating heated rolls and then passed around a pair of heated draw rolls rotating at a speed to impart a draw ratio of about 6 to 1 to give a total denier of approximately 1,300 and then wound on a bobbin. The yarn is plied 8 turns per inch, 3 plies are then twisted in reverse direction 8 turns per inch to form a cord referred to as 1300/3,8/8.

The polyester cord having the modified finish of this invention is then treated with a 20 percent solids dispersion of a conventional RIF/L adhesive composition made in accordance with the following formula in amount sufficient to give a dry solids pick up of from 6 to 7 percent.

R/E/L Adhesive The RIF/L adhesive composition was prepared by adding 98 parts of the resorcinol to 196 parts of water, followed by the addition of 53 parts of formaldehyde. The resulting mixture was aged for 1 hour and then 1,152 parts of terpolymer rubber latex was added. The resulting mixture was aged for a period of 72 hours. After aging, the balance of the water was added. To 65 parts of this RIF/L composition was added 35 parts of a resinous formula: 1 10 parts of resorcinol, 25 parts by volume of formalin (37% formaldehyde in methanol and water), andv 20 parts by volume of water was reacted together in a reaction vessel equipped with both heating and cooling coils, a reflux condenser and a suitable agitator. The mixture was heated to reflux temperature 100 C.) and allowed to remain at this temperature for 15 minutes, after which an additional 30 parts by volume of formalin was added to, the reaction mixture over a period of 10 minutes. After being refluxed for an additional 30 minutes, the resin formed in the reaction vessel was allowed to cool to room temperature. A thick, syrupy resin (for convenience referred to as Resin A) containing 60 percent solids, a viscosity of 750 cps. and a pH of 7 was obtained.

Twenty parts of the Resin A described above is reacted with 6 parts of polymethylene polyphenylisocyanate for 48 hours at 72 F. At the end of this time, the resulting reaction mixture is treated with 0.1 part of sodium hydroxide and 100 parts of water. The resulting neutralized resin-blocked polyisocyanate was allowed to age for 8 hours to produce a clear supernatent layer of soluble resin-blocked polyisocyanate (and for convenience to be referred to as Resin B). 1

To 65 parts of the RIF/L adhesive composition described above is added 35 parts of Resin B and allowed to age at 72 F. for 4 hours.

The polyester cord 1300/3 (Dacron) is passed through a dip tank containing this adhesive. The dipped cord is then dried at 450 F. and embedded in rubber compounded as shown below.

Parts by Weight In compounding the rubber stock in accordance with w the formulation set forth above, a masterbatch of ingredients 1 and 2 are made with the carbon black and mixed on a mill to a temperature of about 100 C. and may be mixed at a temperature as high as 140 C. The resulting carbon black masterbatch is then cooled and the remaining compounds are mixed into the, batch in the order indicated above to a temperature of about C. and may be mixed at a temperature as high as C. I

The following ratings are based on a control using the identical finish, cord and rubber but without the addition of an adhesion promoting agent to the finish. Amount of additive is in percent by weight based on the total weight of the finish solids present in the finish.

Rating Example Additive Amount Percent Peel Force (1) l EPCP 10.0 1 l4 2 EPCP 15.0 l 16 3 EPCP 20.0 1 l9 4 EPCP 25.0 140 5 EPCG 10.0 1 6 EPCG 15.0 1 l8 7 EPCG 20.0 1 19 (1) Feel adhesion is determined in the following manner, Onto the surface of :1 l2 mil thick sheet (12'' X 12'') of rubber (MRS) is laid the treated cords at the rate of 18 per inch which are then covered with a second sheet 12'' X 12') of 12 mil gauge rubber (MRS). This sandwich" arrangement of rubber cord and rubber is then doubled onto itself with a piece of Holland cloth extending one inch into the doubled assembly from the open end from which assembly is clicked l" X 3" samples. which samples are then cured in a mold at 340 F. for 10 minutes. The cured sample is then placed in an lnstrnn machine, heated at 250 F. and the two strips of rubber separated by the Holland cloth are then moved in opposite directions at the rate 012" per minute to determine the average force (A) required to separate the remaining portion of the nample. Depending on the adhexion developed between the cord and rubber. separation either occurit at the rubber/rubber interface or the rubber/cord interface or at both in varying amounts. After nepuration has been completed. the amount of rubber remaining (ll) on the cord is determined by virtual inspection.

The present invention may be used in the manufacture of a pneumatic tire of conventional present day design as shown, for example, in such US. Pat. Nos. as 3,157,218; 3,160,191; 3,160,192; 3,217,778; 3,225,810; 3,225,812; 3,244,215; 3,253,633 and 3,253,638 all of which show a vulcanized rubberized fabric carcass of generally torodial shape having a tread portion superimposed and bonded to the crown area of the carcass and plies of rubberized fabric forming sidewalls extending from the tread over the carcass to the bead portion.

While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in this art that various changes and modifications may be made therein without departing from the spirit or scope of the invention.

What is claimed is:

l. A tire yarn finish consisting essentially of a lubricating oil, an antistatic agent, an emulsifier, water and a polyepoxide resulting from the reaction of epichlorohydrin with a composition selected from the group consisting of pentaerythritol and glycerin, the resulting polyepoxide being substantially soluble and emulsifiable in water and containing in excess of 0.2 epoxy group equivalent per grams of polyepoxide, the polyepoxide being present in the finish in an amount of from about 0.05 part to about 30 parts per 100 parts by weight of the lubricating oil. 

